In large saucepan, heat oil over medium-high heat. Add onion and cook until soft, about 5 minutes. Add carrot, celery, garlic, rosemary, thyme, and bay leaf, and cook 5 minutes more.
Stir in water, tomato paste, and chickpeas with liquid, and cook 10 minutes. Discard bay leaf. Remove 1 cup of mixture from pot and puree in blender; stir back into stew.
Reduce heat to medium-low, and stir in broccoli and cauliflower. Cook until vegetables are crisp-tender, about 7 minutes.