FRANKFURT—Euro zone inflation will take longer to fall back to target than earlier thought but so far there is no evidence that high prices are becoming embedded in wages, ECB Vice President Luis de Guindos said on Wednesday. High inflation is challenging the ECB, which has little experience dealing with rapid price growth and complicates a crucial policy decision due on Dec. 16. While the ECB has maintained that inflation is temporary and will come back under target on its own, a growing number of policymakers are voicing their concern that a less benign outcome is also possible, so the bank should curb stimulus. While largely repeating the ECB’s recent stance, de Guindos acknowledged that inflation risks were “moderately” on the upside and the drop would be slower than once thought. “We are fully convinced that inflation will start to decline at the beginning of next year and in the …