To make pie wedges more visually prominent, you can separate them from the pie.
To move a single wedge away from the center of a 2D or 3D pie chart, select it and then drag it or drag the Explode slider in the Chart inspector.
To move multiple wedges away from the center of a 2D or 3D pie chart, hold down the Shift or Command key while selecting the wedges you want, and then drag them or drag the Explode slider in the Chart inspector.
To separate all the wedges away from the center of a 3D pie chart, select the chart before dragging the Explode slider in the Chart inspector.
You can add a series name or data point label to distinguish individual wedges even further. See Customizing Data Point Symbols and Lines in Line Charts.