"Inserts *on* the valve guides"???
Sounds kind of oxymoronic. ..
A good machine shop will install new guides, ream to size and either cut the seats (if it won't leave the valve too deep) or shrink new seats into the head.
If you're talking about knurling the inside of the guides, please don't.
That's never a long term solution.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.