I don`t think there is any need to change the idler and tensioners IF the bearings are alright. It depends however on your experience as to whether you can correctly ascertain that the bearings are still ok . They are sealed so they should still have all the original grease in them but check visually to see if the seals are in fact still ok. The material the seals are made of normally doesn`t deteriorate and as the car has gone through obviously a relatively small number of cycles and well under the change cycle use, merely need a checkover in my opinion as an ex Euro garage proprietor. If I still owned my workshop however and you came in as a customer, out of safety I would change ALL belts , tensioners, idlers and water pump. It is only on my own vehicle that I would reuse , if ok and properly checked.- a considered risk. That cambelt though needs changing, just as a safety precaution and if the car hasn`t had much use I wouldn`t trust the water pump, they do pack up through lack of use as well as a lot of use. They can also give way without audible warning as I found to my cost in a little used re km`s TS of mine.