Just had a thing come up on my 98 GMC K1500 truck. When braking under medium brake pressure, I get a slight grinding noise from the front, just before the truck comes to a stop. This started a couple days ago, but today was the first day I could take the wheels off and look at it. All four wheels have excellent brake linings, and I see no scoring on the drums or rotors. Front pads & rotors were replaced (by me) less than 5,000 miles ago.
Yes, its not ABS. That makes a much louder sound, and creates a vibration that can be felt in the brake pedal. I was going to take it in soon anyway to get the front end worked on after it was hit over the winter, I guess that just has to be a bit sooner.
Try this. Go and find a parking lot and roll the windows down and drive around in a tight circle to the left and listen for the left wheel bearing grinding. Turning full lock puts more pressure on the wheel bearings. Then streighten it out and see if the noise goes away or changes /lessens. Try it in the opposite direction also to check the right one.
Sometimes if you have a wheel bearing issue, you can tell doing this as the growling noise will be louder when turning and lessen when streightening out.
I agree the wheel bearings should be the next thing checked. Don't wait long. If it's a wheel bearing grinding it will likely soon turn into a popping noise where the bearing has gone completely out leaving you stranded on the side of the road. Usually if it's a wheel bearing if you'll jack up each corner and check there will be movement in the hub area of the bad bearing. GasUser was right the wheel bearing noise will usually be more noticeable in turns and curves.
I went through a whole bunch of wheel bearings on my 2002 GM full size, and unfortunately, the wiggle test isn't very useful. If it fails the wiggle test then you know it's bad, but often they grind without failing the wiggle test.