Changed mine out at 95,000 miles on our UK Mitsubishi Carisma -
4G93 1.8 litre SOHC engine. If the water bearings seize and strip the teeth from the timing belt = potential for major engine damage ?
Not worth the risk in my view. But beware some non OEM pumps - they can be rubbish !
I fitted a non OEM pump to a family Nissan Micra 1.2 litre and it lasted 9 months before leaking ...)