Are body piercings and jewelry wrong?

Leviticus 19:28 refers specifically to making cuttings in the flesh "for the dead." This refers to cutting the flesh as a part of a pagan (and probably superstitious) practice. By the way, that would include circumcision if in fact, the circumcision was done to honor or appease some pagan god. We know for sure that circumcision was practiced in Egypt and elsewhere, but not for the same reasons God had in mind when He commanded it for Abraham and his offspring. So what is condemned here is any cutting of the flesh, including circumcision, that is directly connected with pagan religions or superstitions.

In Exodus 21:6, a Hebrew servant who loved his master and wanted to continue serving him after his six years of service had expired could do so. His master was to "bring him to the judges" and "pierce his ear with an awl." The piercing was for publicly identifying the man as a permanent servant. From this, we can see that Leviticus 19:28 does not condemn all piercings, irrespective of the purpose.

Wearing jewelry, in itself, is not sinful. God's own description of His love for Jerusalem suggests that He doesn't think so, either. Notice Ezekiel 16:10–14:

"'I clothed you in embroidered cloth and gave you sandals of badger skin; I clothed you with fine linen and covered you with silk. I adorned you with ornaments, put bracelets on your wrists, and a chain on your neck. And I put a jewel in your nose, earrings in your ears, and a beautiful crown on your head. Thus you were adorned with gold and silver, and your clothing was of fine linen, silk, and embroidered cloth…. You were exceedingly beautiful, and succeeded to royalty. Your fame went out among the nations because of your beauty, for it was perfect through My splendor which I had bestowed on you,' says the Lord God."

Here, the jewelry (including the nose jewel and earrings) and fine clothing are used by God Himself to symbolize His own splendor. It seems extremely unlikely that God would have created this picture of Himself adorning Jerusalem with ornaments, bracelets, earrings, etc., had He considered the wearing of these things to be sinful.

Isaiah 3:16–26 does not condemn jewelry or in any way suggest that God opposes the wearing of it. What God opposes is the haughtiness or prideful spirit of the "daughters of Zion" (verse 16). They were using their jewelry and their perfumes and their fine clothing to express themselves in this unholy way, but there is nothing inherently evil about those items, and there is certainly a proper use for them. There is nothing wrong with a woman wanting to look her best. There's a huge difference between that and the haughty spirit described in this passage.