In a heavy medium saucepan, heat oil over medium heat. Cook onion, stirring often, until golden brown and soft, about 10 minutes.
Add rice; stir to coat. Stir in wine; cook until reduced by half, about 3 minutes. Add 1/2 cup broth; simmer, stirring, until almost all is absorbed. Add remaining 2 1/2 cups broth, 1/2 cup at a time, stirring until liquid is absorbed before adding more, about 25 minutes total.
Stir in beets, butter, and Parmesan; season with salt and pepper. Serve immediately.