Did you prep the surface and use a self-etching primer? If you don't mind maintenance touch ups maybe you can try the Rustoleum spray on bedliner in a can. That's what I used...it goes on pretty smoothly and blends very easily if you need to touch it up down the road. The finish is more like a fine grit sand paper finish, and it's pretty much rock hard once it dries. What I noticed on my sliders is after stepping on it for one winter the "grittyness" seems to have worn off some on the spots where I step the most. I plan to shot a few coats over when the weather gets warmer.
Traditional bedliners like rhinoliner or line-x would be great, but if you plan to use the sliders as...a
slider, that's not going to last long at all and touch up would be a pain.
One other option is, having your sliders powder coated and then spray on the Rustoleum bedliner over it. Powder coating is generally a bit tougher when it comes to chip resistance, but of course nothing is impervious to impacts from rocks and such. This is what I had done because I suck at paint prep work
I had Bud powder coat them in his standard textured black finish (for the paint to adhere to better), and then when I got them, I sprayed on several coats of the Rustoleum bedliner over it. This way I have the best of both worlds in that I can easily touch it up in a matched finish whenever I feel like it, and I have the durability of powder coat.