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if the rolex cases are cast, and they may well be, those voids in the 1st image are what are called "negatives" where the molten metal didn't fully flow or there was air or gas trapped in the mold, or possibly the casting was pulled from the mold too early and cooled too fast at that lug with the metal contracting. I would expect pitting would not be striated like in that image, but rather pocked marked like the result of small pox.
Reason they're called negatives, they're the opposite of "positives" - ie, the cavity mold itself had pitting in it (depending on the type of casting) and molten metal ends up filling the voids in the cavity mold - and you get "bumps" or lumps on the surface of the casting
I'm not a metalurgist, but did work with castings. Hopefully a metalurgist will pop in and give his assessment
fwiw
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