First off, are you sure that your bike is from 2008?
Because from 07 onwards all R, S, and GT models have got the new ATE ABS unit, which has only one pump motor.
You are describing a fault that is from an 05-06 Servoassisted brake system. Low pressure indication "Front" or "Rear" is either from having an air bubble in the system or because of a faulty pressure sensor.
Each sensor is a ceramic plate at the opposite end of the hydraulic unit. Prone to fail.... other people have had water destroy the circuit board.
Worn down brushes are obviously not good, but as long as the pump motors are running, there shouldn't be a problem.