It depends on what Jewels and what Malawians. Definetely none of the larger Jewels like the H. frempongi, H. elongatus, or H. fasciatus. Also, if you are looking to breed the Jewels, then you run into trouble.
They are some of the best yet most aggressive fish when it comes to defending a spawn. I'd go wit ha small jewel species and a fast and large semi-aggressive mbuna in a large tank, at least a 75.