The book "Design & Creation of Jewelry" by Robert Von Newman is a good source as well as "Metal Techniques for the Craftsman" by Oppi Untract. There are others who have covered this topic. I would look for resources showing the marriage of metals as well as the inlay of metals.

Fred Zweig
Metalsmith

I've inlaid stone and wood into fabricated silver pieces. That was pretty much a lot of repeated grinding and fitting. It doesn't sound like what you're after, though. The book Fred mentioned has some good information on inlaying metal. Traditionally, gravers and chisels are used to create depressions with undercut edges and toothed surfaces into and onto which softer metal can be applied. I imagine a milling machine might be put to good use if you're inlaying into knife blades. Your question reminded me of something I made note of years ago-and I'm glad I was able to find it again, so I don't have to try to explain it--The Two-legged Parser.
www.watchman.dsl.pipex.com/ two-legged%20parser/parser.html
They say knife makers used these for basic inlays.