Is there a way to add anchored images into text (a la InDesign) in After Effects?

You could get fancy and use sourceRectAtTime().width to get the width of two text layers and combine the layer size/scale or shape layer size plus a padding variable to keep the two text layers lined up with the graphic in between them. Justify the first line Right, justify the second line Left, then put the graphic below them both and add these expressions to a shape layer graphic centered on the anchor point, and you have it.

// First line position
shapeLayer = thisComp.layer(index + 2);
slScale = shapeLayer.scale[0] * .01;
slWidth = slScale * shapeLayer.sourceRectAtTime().width / 2;
slPosition = shapeLayer.position;
pad = 50;
x = slPosition[0] - slWidth - pad;
y = slPosition[1];
[x, y]


// Second line position
shapeLayer = thisComp.layer(index + 1);
slScale = shapeLayer.scale[0] * .01;
slWidth = slScale * shapeLayer.sourceRectAtTime().width / 2;
slPosition = shapeLayer.position;
pad = 50;
x = slPosition[0] + slWidth + pad;
y = slPosition[1];
[x, y]

The comp looks like this:

I have uploaded a project file.