This sounds like what you are talking about:
Order an 8 32 threaded insert for your project. These 8-32 threaded insert pieces are made in the USA and easy to install.. Additionally, our 8-32 x 6/16 threaded inserts will seal against liquids and gasses. Shop for 8-32 threaded metal inserts with E-Z LOK.www.ezlok.com
Interesting, that the outside threads come preheated with Loctite.
I have used the brass inserts designed for wood ("knife edge) in the past for making jigs, and I can confirm that they are challenging to install straight. I think I'll give these a shot. Looks like they are about $1 each in packs of 10.
Thanks, I'll order some and try them out.
If the inserts have lock-tite on them, you'll definitely want to remove the lock-tite before installing them in wood
A wire brush and some solvent like lacquer thinner should do it
You'll also want to make sure you use a "bottom" tap with the inserts with the 5/16"-18 external thread - a "bottom" tap will cut deeper threads closer to a hole's bottom than a taper or plug tap will