What to expect
Begin day one with a section of the Miraflores Malecón. Choose somewhere to eat in Barranco and travel there; the connection need not become another walk. Visit the Puente de los Suspiros and its surroundings if you feel like exploring further. Day two focuses on the historic centre: choose one interior visit that interests you and leave time to look at the architecture outside.
How it fits into a journey
If you arrive through Jorge Chávez, the first Callao stop represents only your arrival transfer to Miraflores, not another city visit. The two sightseeing days start after that arrival. Use one accommodation base; this plan does not require a hotel change. Arrange transport to each day's first visit and back from the last. Callao can be an extra outing on another day, not a compulsory fourth stop.