metal on metal sound while turning

That happened to me too. Took it in to see what was up and all I needed was new rear brake pads. The rotors needed to be sanded down a little too. That's what was making the metal-on-metal sound. The noise went away after I got the new pads.

FYI - Take a look at your rotors closely and check to see if there looks like there's unusually deep grooves on the surface. Compare each side front and back.