URL Rewriting in asp.net MVC

You need to create a create MapRoute for each of the URL, above Default route in Route.config suppose, you want to show user/index  as default page, so route should be

routes.MapRoute(
              name: "DefaultNew",
               url: "{controller}/{action}",
               defaults: new { controller = "User", action = "Index" }
           );

for http://localhost:5130/customer add another value in route config above defaultnew/default ruote

 routes.MapRoute(
                name: "PostWithSlug",
                url: "customer",
                defaults: new { controller = "Customer", action = "Index" }
                );

check these links for more help

https://qawithexperts.com/questions/259/show-a-slug-url-without-id-in-the-url-in-aspnet-mvc

https://qawithexperts.com/questions/37/how-can-i-simplify-url-in-net-mvc

Hope this helps