There's no issue and that's not wear. It's not uncommon for those to look like a rat chewed on them. I've looked at a brand new pistol that looked the same and the right forward "rail" on my CW9 looks very much like your picture.
I put "rail" in quotes because those are not the actual rails, the actual rails are metal. The rear rails are at the extreme rear of the pistol and the forward rails are down in the dustcover channel. You can see them with the gun disassembled--in fact, the rear part of the left forward rail is visible in the upper right hand corner of your picture.
The forward rails engage the lower front part of the slide about on a level with the recoil spring. You can see the grooves on that part of the slide even with the gun assembled.
I'm not sure exactly why the polymer rails are there--they don't actually provide any support for the slide, that's all done with the metal rails. Maybe they're there to help get the slide lined up for assembly.
I've attached some pictures showing the actual position of the forward slide rails, the grooves that accommodate them in the slide and also (although my picture's not that good) the partially missing right side "rail".
