Q: I replaced my serpentine belt on a 2013 chevy sonic. But it must be rubbing on something because it scraped the inside edge

The first thing to do is verify that you have the correct belt (part number) installed. If the belt is the correct one specified for your vehicle, the principal cause of what you describe are pulleys and/or rotating elements (harmonic balancer, a/c compressor, alternator, etc.) that are not all turning in the EXACT same plane. Also, all rotating elements should be checked for smooth operation. Over time, the grease in the bearings in pulleys will dry out and the pulleys might then present too much resistance. And, yes, the tensioner should be checked, too. If you want the required diagnostic and inspection steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a drive belt diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.