I purchased a new pair of 510 v4 NB shoes July 17 2019. The left shoe is now worn thru on the inside of the shoe on the left shoe. Is this normal?

This is definitely not normal. Shoes I buy from New Balance typically last for a couple of years and I run about 5 to 7 miles per day. I would suspect that you either have counterfeits or you have the wrong size shoe. When you go to the New Balance store they won't sell you shoes without a fitting to ensure you get the proper shoe

Bought them thru Amazon.

Hey Gary- We don't carry that shoe- where did you buy it? We guarantee our shoes, so next time come to see us :)

Umm, might want to give them a call.