The first interview was with the country that sponsors the JPO, they assessed my fit with the JPO program, my background knowledge (e.g., why this country sponsors the program, the benefit for the World Bank, etc.), and whether I'm fit for a long-term career in international organisations. They also asked one scenario question and two behavioural ones (a situation in which I had to change course, a challenge when working with an international team).
The second interview was with three team members from the World Bank. They asked for my motivation, examples when I worked on technical and thematic requirements of the job, example for teamwork, conflict, and prioritization, and challenges I see for this field.