Here is a rather long discussion about doing precision inlay. There are various techniques to consider and also ways to approach. I have finally settled on using the expanded stroke and then break apart to use the outer line as the cut for the inlay and the inner line to become the shape of the engrave.
Engraving on hardwood to put an inlay is tough because grain does not allow a flat surface. discovered that with my inlay compass rose.
You have test test on the material. It is a combination of speed and power resolution and number of passes. You don’t want to burn it too bad because soot builds up, but also don’t want to take forever.
TLDR:
Here’s @dannyc’s post that sums it up best for Inkscape.