1993 Chevy Blazer Brakes locking up when wet

I have had my brakes worked on all kinds of ways. I have had the brake drums and shoes replaced and all kinds of adjustments done. However, my brakes continue to lock up when they are wet. If it rains a good amount outside or if you let it set overnight, the rear brakes lock up and the ABS systems kicks in. But this is only when going under 10 mph. After a few stops it goes away.