Wire inlay, just as carving, or engraving, is a craft unto itself. I can explain to you how it is done though. First, draw your art on the stock, it is a lot easier if the wood is in the white. cut the groove the wire will fit into. I cut the grooves using little tools I make, the shape of which I would have to show in a picture, but really I am punching the wood in, rather than cutting. Place ribbon (I say ribbon because the wire is actually a flat piece of strip about an 1/8th of an inch wide) roughly shape the ribbon to your design, press or tap it into your groove, and then wet the wood a bit to get the wood to close back in on any loose spots.
As with engraving or carving, sometimes the wire must be thinned at junction points to give a good flow to the artwork, and as with all artwork it takes time to learn to do it and make it look as it should. Also, there are a few tricks to getting the ribbon to set and stay in place, one of which is to raise a wire edge on the inner edge of the ribbon so once the wood compresses back it will trap the bottom edge. There are a few other tricks in the book on doing this work well, but that takes time and experience. I use no glue though to do this work.