ABS PUMP OR HUB PROBLEM?

Hi, I have a strange problem with brakes of 2004 TDI. At low speeds the ABS kicks in, from reading all the forums here that suggests ABS Hub (reluctor plate). However, there is no ABS light on and a quick pump on foot pedal at 30 gives a similar feel (but no wheel lock on and off). Is this the ABS pump or part of the pump that has gone? A friend of a friend who works ina dealership says there is sometimes a fault with the pump that sounds similar.

Anyone out there who ha had this and solved it? Cheers.