That wasn't done with an electric pencil, that was done with a laser engraver and is deeper than it appears in the pic.
How'd they manage to get every example of a letter or number, so different from each other then? Not too many freehand operated Laser Engravers, I figure.
Or was it yours at some time?
LOL! at the 'harmonics' worries.
The way I see stuff like that, is that it's pretty much like a tattoo. You pretty much live with it the way it is, or cover the area with something bigger and uglier.
If the numbers themselves are the issue, get an Electric Pencil, make up a metal shield for a protective stencil, and proceed to 'stipple' the whole area to your satisfaction, obliterating them.
If you wanted to get really Artsy, inlay a plate of silver or gold and have a name engraved on it (your kid, your Mom, someone Famous (so you can tell whoppers about them owning it) etc. over the location.