Uneven wear on brake pads is usually a sign of sticking caliper slides.
Disc brakes are designed so that the piston applies the force from one side of the caliper, but the caliper slides on the steering knuckle so that it centers itself on the rotor in order to apply an equalized clamping force to both sides of the rotor. (I hope that I'm explaining this well enough.)
As the friction material wears, the piston extends further and further out of it's housing in the caliper. When you install new pads, you have to push the piston back in it's bore until the new pads clear the rotor. The way that I do that is to loosen the bleeder screw, and compress the piston back into the caliper using a C-clamp.
So inspect, clean, and lube the caliper pins, bushings, and sliding surface on the steering knuckle. Use a silicone-based "disc brake caliper lube" like Permatex #31877 (which is a 5 gram "counterman's choice" retail pouch containing enough lube for a single application.)