Will prolong use of Nexium (esomeprazole) bring any harm?

Maybe. Generally very safe but increased rates of fractures (possible calcium problem), infections and low magnesium has been reported. Best to take only if needed and then at the lowest dose possible.
Possibly. Prolonged use of Nexium (esomeprazole) and other drugs in its class can reduce absorption of calcium and some vitamins. It has also been implicated in worsening osteoporosis.