Brake pad/caliper problem?

[C2K]

In all honesty, I doubt it's any of the above although they're worth checking.

I suspect your pads are a tight fit in the carrier, and the caliper is forcing that pad to pivot rather than slide, hence wearing on the outside where the force is being applied. Take the pads out the caliper, wire brush the carrier where they locate, and be prepared to file a little off the edges.