Just enjoy what you got, if the stem is in good shape and your a pipe smoker (rather than someone that puts it in a display case) then just enjoy it with the original stem, the inlay has no effect in the quality of the smoke and I am sure the pipe looks fine without it. Besides anyone other than Savinelli doing it is basically doing a really good forgery, Savinelli will only be able to do the real deal but then you are not going to get a vulcanite stem either... As far as I know having the original stem is more valuable than a replacement stem, even by the same company, the fact no one can see the brand on the stem shouldn't make it less valuable to you, but will only make it harder to resell.
I'm totally with Eric on this. We don't smoke the logo.
Now I am getting a replacement stem made by Dave Wolff for a Charatan Executive After Hours; it should be ready in a couple weeks. The original stem's logo shows some wear but the vulcanite is in near perfect shape. The reason I'm getting the replacement stem made is to smoke the pipe with the replacement stem and thus "save" the original DC stem so it will remain pristine.
It's clear this logo/signature is important to you. If your original stem is in good shape, may want to contact Dave Wolff (or Tim West, or Norwood, or another respected professional) about the possibility of having the signature/autograph "decal" inlaid on your original stem. If that can be done (they do it for Dunhill, Charatan, and some other brands), it wouldn't cost much.