Water pump, pulleys bearing damage?

Hello like-minded people. In July, after some searching, I enjoyed a specimen which was already extremely close to my requirements. It is a GP3 with approx. 126’km. I also like to drive the car very much. Wouldn’t like to get out of the car at all. But well… there’s also a life outside of these rolling juices. Is really a class car that doesn’t fit into the VW Group at all. Unfortunately, now noises are coming up that make me nervous at every start. It sounds like a whining/singinging in idle run. At higher speed it gets less. At higher temperature, too. Well, my question….if it’s the pulley rollers – how long do they last? Do you hear a water pump damage before and how does it sound? Oh yes….the dealer had had the tooth belt changed before delivery. Is now no 3000km ago. Then I’m still interested in the running behavior of the V8. I usually know a very quiet run. With my speed fluctuations of about 30 to 40 rpm, which I can feel in the interior. In case of error, however, there is no problem memory?