Most 'semi-metallic' brake pads are basically steel fibers (think chopped steel wool) mixed with various fillers and binding agents. If the pads are poorly constructed, you can have "hard spots" right out of the box. Also, a large number of the brake rotors out there are the "Made in China" variety, and quality of the metal in these can be spotty. If turning the rotors doesn't solve the problem, make sure you get premium quality parts when you replace the brakes. You might pay a little more, but the results are usually worth it. Good luck.
