Pineapple Upside Down Bundt Cake

Ingredients
1/2 Cup butter (1 stick), melted
1/2 Cup packed brown sugar
1 Can pineapple rings in 100% juice (reserve the juice)
1 Jar maraschino cherries
1 Box yellow or pineapple cake mix
1 4-serving box instant vanilla pudding
3 eggs
Vegetable oil
Milk