You are correct to be concerned-- babies should get the bulk of their nutrition from breastmilk/formula for the first year. My baby really likes solids, and would probably do the same if I let him. I called a lactation consultant. She said always breastfeed right before giving solids. In the morning, I don't feed solids until he has had a good breastfeeding. Same at lunch and dinner. This seems to help a lot. Also, for a few days, I pumped for about 8 min., 4 times per day to get my milk supply up. This seemed to increase my flow and his interest in breastfeeding.
I've found the lactation consultants at United Hospital (St. Paul) incredibly helful! You can reach them at ###-###-####.
Best of luck!