Toss the beef cubes with the flour, salt, and black pepper in a bowl until evenly coated.
Heat the olive oil in a large skillet over medium-high heat. Brown the beef in batches for 3 to 4 minutes per side, then transfer it to the slow cooker.
Add the mushrooms, onion, carrots, and garlic to the slow cooker.
Stir in the red wine, beef broth, tomato paste, thyme, and rosemary until the tomato paste dissolves.
Cover and cook on low for 8 hours until the beef is fork-tender.
Taste and adjust salt and pepper before serving.