I have a manual tensioner on my 2016 Versa, I assume you have the same manual tensioner on your 2017. There is a gauge that you use to set the proper amount of tension on the belt. The pulley is a different part than the actual tensioner. There would be a bolt in the middle of the pulley that allows for removal and replacement.
Again, until you remove the belt and check each pulley, it is hard to say which pulley may or may not be bad.