Wegmans is a US grocery retailer I did not know much about, as I have mostly lived in California, whereas Wegmans is on the East Coast (Greater New York Area). It is a familly operated business of a pretty large size, with 77 stores.
A perfect employer: employees are well treated and love to work at Wegmans. Same thing for Costco, another outperforming retailer. Customer relationship is key in retailing, and by having appropriate staff management, you have employees that will share their happiness on being there.
An amazing customer experience: beyond the conctact with employee, Wegmans put a lot of effort in merchandizing, in order to create a warm place where customers love to spend time to shop. The way the store is set up allows to have breaks with different "environment" or "ambiance".
A pioneer: They are most of the time the first to adopt new technologies to help customer experience.
Be active in the community: to have clear mission statement and proper value, it matters bond with the community.
To go a bit furhter, I invite to check the 25 reasons why Wegmans is loved by its customers. Below couple of chosen picks. Actually, I have also been impressed by their website: simple, full of interesting content.