We are both on Medicare A & B. "A" is free to all Seniors, but "B" has a monthly premium cost and yearly deductible. If you are lucky, the monthly premium can not even be owed. Actually, my wife chose Medicare A & B, instead of the company medical insurance where she works.
Our supplement is Florida Blue, but Medicare has to pay before Florida Blue pays anything.
We also have Humana Walmart Rx Drug Plan, which definitely isn't the best Plan.
Once the yearly deductible for Medicare "B" is paid, it pretty much covers the total costs of other things. My left rotator cuff surgery costs around $35k, but we only paid about $400 or so total. My Physical Therapy was completely covered by Medicare as well.